1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile employing an electrophotographic method or an electrostatic recording method, and particularly an image forming apparatus using a cleaning blade.
2. Description of the Related Art
Conventionally, a cleaning blade composed of an elastic material such as urethane rubber has been widely used as a cleaning unit for cleaning residual toners and the like.
Rubber materials such as urethane rubbers that have high hardness, and are rich in elasticity and excellent in abrasion resistance, mechanical strength, oil resistance, and ozone resistance are commonly used as the rubber material for the cleaning blade.
A slippage between an image bearing member and a blade is primarily maintained by toner or an external additive contained in the toner, but an amount of the toner that reaches both ends of the image bearing member is much lower than an amount of the toner that reaches a central portion of the image bearing member. Thus, the slippage of the cleaning blade is not maintained, and a phenomenon that the cleaning blade is wrongly turned up with starting from an end of a lengthwise direction (hereinafter, blade turn-up) occurs easily.
In recent years, the invention for reducing the blade turn-up in which a cleaning blade is processed by impregnating a total lengthwise area of the rubber material that forms the cleaning blade with an isocyanate compound, and by applying isocyanate onto the ends in the lengthwise direction of the cleaning blade to increase a rubber hardness of the end of the lengthwise direction and lower a coefficient of friction with the image bearing member has been discussed as a method for preventing the blade turn-up (Japanese Patent Application Laid-Open No. 2009-63993).
However, when a section subjected to treatment to increase the hardness is formed on the both ends in the lengthwise direction of the cleaning blade, a difference in level may occur at an internal end of the treated section (hereinafter, a section treated with high hardness), which is a border between the section treated with the high hardness and an untreated section upon abutting the cleaning blade on the image bearing member, by swelling of the section treated with the high hardness. In addition, the toner sometimes escapes from the difference in level.
Further, in the image forming apparatus using an intermediate transfer member, it is likely that the toner that escapes from the cleaning blade on the image bearing member is transferred and accumulated on the intermediate transfer member and subsequently transferred onto a recording material to cause image defect.